]> git.bitcoin.ninja Git - rust-lightning/commitdiff
Lock outbound channels at 0conf if the peer indicates support for it
authorMatt Corallo <git@bluematt.me>
Tue, 1 Feb 2022 21:57:01 +0000 (21:57 +0000)
committerMatt Corallo <git@bluematt.me>
Fri, 27 May 2022 22:40:07 +0000 (22:40 +0000)
If our peer sets a minimum depth of 0, and we're set to trusting
ourselves to not double-spend our own funding transactions, send a
funding_locked message immediately after funding signed.

Note that some special care has to be taken around the
`channel_state` values - `ChannelFunded` no longer implies the
funding transaction is confirmed on-chain. Thus, for example, the
should-we-re-broadcast logic has to now accept `channel_state`
values greater than `ChannelFunded` as indicating we may still need
to re-broadcast our funding tranasction, unless `minimum_depth` is
greater than 0.

Further note that this starts writing `Channel` objects with a
`MIN_SERIALIZATION_VERSION` of 2. Thus, LDK versions prior to
0.0.99 (July 2021) will now refuse to read serialized
Channels/ChannelManagers.

lightning/src/ln/channel.rs
lightning/src/ln/channelmanager.rs
lightning/src/ln/priv_short_conf_tests.rs
lightning/src/util/config.rs

index a0b19920fcade856945889075f3aa1899d9da00e..f221ee6227c7a4f09482050ed31363ef843272ea 100644 (file)
@@ -710,6 +710,11 @@ pub(super) struct Channel<Signer: Sign> {
        // Our counterparty can offer us SCID aliases which they will map to this channel when routing
        // outbound payments. These can be used in invoice route hints to avoid explicitly revealing
        // the channel's funding UTXO.
+       //
+       // We also use this when sending our peer a channel_update that isn't to be broadcasted
+       // publicly - allowing them to re-use their map of SCID -> channel for channel_update ->
+       // associated channel mapping.
+       //
        // We only bother storing the most recent SCID alias at any time, though our counterparty has
        // to store all of them.
        latest_inbound_scid_alias: Option<u64>,
@@ -1987,12 +1992,6 @@ impl<Signer: Sign> Channel<Signer> {
                if msg.minimum_depth > peer_limits.max_minimum_depth {
                        return Err(ChannelError::Close(format!("We consider the minimum depth to be unreasonably large. Expected minimum: ({}). Actual: ({})", peer_limits.max_minimum_depth, msg.minimum_depth)));
                }
-               if msg.minimum_depth == 0 {
-                       // Note that if this changes we should update the serialization minimum version to
-                       // indicate to older clients that they don't understand some features of the current
-                       // channel.
-                       return Err(ChannelError::Close("Minimum confirmation depth must be at least 1".to_owned()));
-               }
 
                if let Some(ty) = &msg.channel_type {
                        if *ty != self.channel_type {
@@ -2029,7 +2028,12 @@ impl<Signer: Sign> Channel<Signer> {
                self.counterparty_selected_channel_reserve_satoshis = Some(msg.channel_reserve_satoshis);
                self.counterparty_htlc_minimum_msat = msg.htlc_minimum_msat;
                self.counterparty_max_accepted_htlcs = msg.max_accepted_htlcs;
-               self.minimum_depth = Some(msg.minimum_depth);
+
+               if peer_limits.trust_own_funding_0conf {
+                       self.minimum_depth = Some(msg.minimum_depth);
+               } else {
+                       self.minimum_depth = Some(cmp::max(1, msg.minimum_depth));
+               }
 
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.funding_pubkey,
@@ -2169,7 +2173,7 @@ impl<Signer: Sign> Channel<Signer> {
 
        /// Handles a funding_signed message from the remote end.
        /// If this call is successful, broadcast the funding transaction (and not before!)
-       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, best_block: BestBlock, logger: &L) -> Result<(ChannelMonitor<Signer>, Transaction), ChannelError> where L::Target: Logger {
+       pub fn funding_signed<L: Deref>(&mut self, msg: &msgs::FundingSigned, best_block: BestBlock, logger: &L) -> Result<(ChannelMonitor<Signer>, Transaction, Option<msgs::FundingLocked>), ChannelError> where L::Target: Logger {
                if !self.is_outbound() {
                        return Err(ChannelError::Close("Received funding_signed for an inbound channel?".to_owned()));
                }
@@ -2238,7 +2242,7 @@ impl<Signer: Sign> Channel<Signer> {
 
                log_info!(logger, "Received funding_signed from peer for channel {}", log_bytes!(self.channel_id()));
 
-               Ok((channel_monitor, self.funding_transaction.as_ref().cloned().unwrap()))
+               Ok((channel_monitor, self.funding_transaction.as_ref().cloned().unwrap(), self.check_get_funding_locked(0)))
        }
 
        /// Handles a funding_locked message from our peer. If we've already sent our funding_locked
@@ -3540,12 +3544,13 @@ impl<Signer: Sign> Channel<Signer> {
        /// monitor update failure must *not* have been sent to the remote end, and must instead
        /// have been dropped. They will be regenerated when monitor_updating_restored is called.
        pub fn monitor_update_failed(&mut self, resend_raa: bool, resend_commitment: bool,
-               mut pending_forwards: Vec<(PendingHTLCInfo, u64)>,
+               resend_funding_locked: bool, mut pending_forwards: Vec<(PendingHTLCInfo, u64)>,
                mut pending_fails: Vec<(HTLCSource, PaymentHash, HTLCFailReason)>,
                mut pending_finalized_claimed_htlcs: Vec<HTLCSource>
        ) {
                self.monitor_pending_revoke_and_ack |= resend_raa;
                self.monitor_pending_commitment_signed |= resend_commitment;
+               self.monitor_pending_funding_locked |= resend_funding_locked;
                self.monitor_pending_forwards.append(&mut pending_forwards);
                self.monitor_pending_failures.append(&mut pending_fails);
                self.monitor_pending_finalized_fulfills.append(&mut pending_finalized_claimed_htlcs);
@@ -3559,9 +3564,18 @@ impl<Signer: Sign> Channel<Signer> {
                assert_eq!(self.channel_state & ChannelState::MonitorUpdateFailed as u32, ChannelState::MonitorUpdateFailed as u32);
                self.channel_state &= !(ChannelState::MonitorUpdateFailed as u32);
 
-               let funding_broadcastable = if self.channel_state & (ChannelState::FundingSent as u32) != 0 && self.is_outbound() {
-                       self.funding_transaction.take()
-               } else { None };
+               // If we're past (or at) the FundingSent stage on an outbound channel, try to
+               // (re-)broadcast the funding transaction as we may have declined to broadcast it when we
+               // first received the funding_signed.
+               let mut funding_broadcastable =
+                       if self.is_outbound() && self.channel_state & !MULTI_STATE_FLAGS >= ChannelState::FundingSent as u32 {
+                               self.funding_transaction.take()
+                       } else { None };
+               // That said, if the funding transaction is already confirmed (ie we're active with a
+               // minimum_depth over 0) don't bother re-broadcasting the confirmed funding tx.
+               if self.channel_state & !MULTI_STATE_FLAGS >= ChannelState::ChannelFunded as u32 && self.minimum_depth != Some(0) {
+                       funding_broadcastable = None;
+               }
 
                // We will never broadcast the funding transaction when we're in MonitorUpdateFailed (and
                // we assume the user never directly broadcasts the funding transaction and waits for us to
@@ -3570,7 +3584,8 @@ impl<Signer: Sign> Channel<Signer> {
                //   the funding transaction confirmed before the monitor was persisted, or
                // * a 0-conf channel and intended to send the funding_locked before any broadcast at all.
                let funding_locked = if self.monitor_pending_funding_locked {
-                       assert!(!self.is_outbound(), "Funding transaction broadcast by the local client before it should have - LDK didn't do it!");
+                       assert!(!self.is_outbound() || self.minimum_depth == Some(0),
+                               "Funding transaction broadcast by the local client before it should have - LDK didn't do it!");
                        self.monitor_pending_funding_locked = false;
                        let next_per_commitment_point = self.holder_signer.get_per_commitment_point(self.cur_holder_commitment_transaction_number, &self.secp_ctx);
                        Some(msgs::FundingLocked {
@@ -4552,6 +4567,11 @@ impl<Signer: Sign> Channel<Signer> {
                self.channel_state >= ChannelState::FundingSent as u32
        }
 
+       /// Returns true if our funding_locked has been sent
+       pub fn is_our_funding_locked(&self) -> bool {
+               (self.channel_state & ChannelState::OurFundingLocked as u32) != 0 || self.channel_state >= ChannelState::ChannelFunded as u32
+       }
+
        /// Returns true if our peer has either initiated or agreed to shut down the channel.
        pub fn received_shutdown(&self) -> bool {
                (self.channel_state & ChannelState::RemoteShutdownSent as u32) != 0
@@ -4582,7 +4602,7 @@ impl<Signer: Sign> Channel<Signer> {
        }
 
        fn check_get_funding_locked(&mut self, height: u32) -> Option<msgs::FundingLocked> {
-               if self.funding_tx_confirmation_height == 0 {
+               if self.funding_tx_confirmation_height == 0 && self.minimum_depth != Some(0) {
                        return None;
                }
 
@@ -4759,9 +4779,9 @@ impl<Signer: Sign> Channel<Signer> {
                        // close the channel and hope we can get the latest state on chain (because presumably
                        // the funding transaction is at least still in the mempool of most nodes).
                        //
-                       // Note that ideally we wouldn't force-close if we see *any* reorg on a 1-conf channel,
-                       // but not doing so may lead to the `ChannelManager::short_to_id` map being
-                       // inconsistent, so we currently have to.
+                       // Note that ideally we wouldn't force-close if we see *any* reorg on a 1-conf or
+                       // 0-conf channel, but not doing so may lead to the `ChannelManager::short_to_id` map
+                       // being inconsistent, so we currently have to.
                        if funding_tx_confirmations == 0 && self.funding_tx_confirmed_in.is_some() {
                                let err_reason = format!("Funding transaction was un-confirmed. Locked at {} confs, now have {} confs.",
                                        self.minimum_depth.unwrap(), funding_tx_confirmations);
@@ -5620,7 +5640,7 @@ impl<Signer: Sign> Channel<Signer> {
 }
 
 const SERIALIZATION_VERSION: u8 = 2;
-const MIN_SERIALIZATION_VERSION: u8 = 1;
+const MIN_SERIALIZATION_VERSION: u8 = 2;
 
 impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
        (0, FailRelay),
@@ -5685,12 +5705,10 @@ impl<Signer: Sign> Writeable for Channel<Signer> {
 
                self.user_id.write(writer)?;
 
-               // Write out the old serialization for the config object. This is read by version-1
-               // deserializers, but we will read the version in the TLV at the end instead.
-               self.config.forwarding_fee_proportional_millionths.write(writer)?;
-               self.config.cltv_expiry_delta.write(writer)?;
-               self.config.announced_channel.write(writer)?;
-               self.config.commit_upfront_shutdown_pubkey.write(writer)?;
+               // Version 1 deserializers expected to read parts of the config object here. Version 2
+               // deserializers (0.0.99) now read config through TLVs, and as we now require them for
+               // `minimum_depth` we simply write dummy values here.
+               writer.write_all(&[0; 8])?;
 
                self.channel_id.write(writer)?;
                (self.channel_state | ChannelState::PeerDisconnected as u32).write(writer)?;
index 239b45ebf5ae5f27c2bef956585139ba30b294cc..5f65a66ce914caa8cb454a9d56663c251bbff073 100644 (file)
@@ -1286,7 +1286,7 @@ macro_rules! remove_channel {
 }
 
 macro_rules! handle_monitor_err {
-       ($self: ident, $err: expr, $short_to_id: expr, $chan: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr, $chan_id: expr) => {
+       ($self: ident, $err: expr, $short_to_id: expr, $chan: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $resend_funding_locked: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr, $chan_id: expr) => {
                match $err {
                        ChannelMonitorUpdateErr::PermanentFailure => {
                                log_error!($self.logger, "Closing channel {} due to monitor update ChannelMonitorUpdateErr::PermanentFailure", log_bytes!($chan_id[..]));
@@ -1324,13 +1324,13 @@ macro_rules! handle_monitor_err {
                                if !$resend_raa {
                                        debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst || !$resend_commitment);
                                }
-                               $chan.monitor_update_failed($resend_raa, $resend_commitment, $failed_forwards, $failed_fails, $failed_finalized_fulfills);
+                               $chan.monitor_update_failed($resend_raa, $resend_commitment, $resend_funding_locked, $failed_forwards, $failed_fails, $failed_finalized_fulfills);
                                (Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore("Failed to update ChannelMonitor".to_owned()), *$chan_id)), false)
                        },
                }
        };
-       ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr) => { {
-               let (res, drop) = handle_monitor_err!($self, $err, $channel_state.short_to_id, $entry.get_mut(), $action_type, $resend_raa, $resend_commitment, $failed_forwards, $failed_fails, $failed_finalized_fulfills, $entry.key());
+       ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $resend_funding_locked: expr, $failed_forwards: expr, $failed_fails: expr, $failed_finalized_fulfills: expr) => { {
+               let (res, drop) = handle_monitor_err!($self, $err, $channel_state.short_to_id, $entry.get_mut(), $action_type, $resend_raa, $resend_commitment, $resend_funding_locked, $failed_forwards, $failed_fails, $failed_finalized_fulfills, $entry.key());
                if drop {
                        $entry.remove_entry();
                }
@@ -1338,16 +1338,19 @@ macro_rules! handle_monitor_err {
        } };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $chan_id: expr, COMMITMENT_UPDATE_ONLY) => { {
                debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst);
-               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, false, true, Vec::new(), Vec::new(), Vec::new(), $chan_id)
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, false, true, false, Vec::new(), Vec::new(), Vec::new(), $chan_id)
        } };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $chan_id: expr, NO_UPDATE) => {
-               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, false, false, Vec::new(), Vec::new(), Vec::new(), $chan_id)
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, false, false, false, Vec::new(), Vec::new(), Vec::new(), $chan_id)
+       };
+       ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_funding_locked: expr, OPTIONALLY_RESEND_FUNDING_LOCKED) => {
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, false, false, $resend_funding_locked, Vec::new(), Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
-               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, Vec::new(), Vec::new(), Vec::new())
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, false, Vec::new(), Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
-               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, $failed_forwards, $failed_fails, Vec::new())
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, false, $failed_forwards, $failed_fails, Vec::new())
        };
 }
 
@@ -4268,7 +4271,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                        // hasn't persisted to disk yet - we can't lose money on a transaction that we haven't
                                        // accepted payment from yet. We do, however, need to wait to send our funding_locked
                                        // until we have persisted our monitor.
-                                       chan.monitor_update_failed(false, false, Vec::new(), Vec::new(), Vec::new());
+                                       chan.monitor_update_failed(false, false, false, Vec::new(), Vec::new(), Vec::new());
                                },
                        }
                }
@@ -4299,12 +4302,12 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                        if chan.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
-                                       let (monitor, funding_tx) = match chan.get_mut().funding_signed(&msg, best_block, &self.logger) {
+                                       let (monitor, funding_tx, funding_locked) = match chan.get_mut().funding_signed(&msg, best_block, &self.logger) {
                                                Ok(update) => update,
                                                Err(e) => try_chan_entry!(self, Err(e), channel_state, chan),
                                        };
                                        if let Err(e) = self.chain_monitor.watch_channel(chan.get().get_funding_txo().unwrap(), monitor) {
-                                               let mut res = handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::RevokeAndACKFirst, false, false);
+                                               let mut res = handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::RevokeAndACKFirst, funding_locked.is_some(), OPTIONALLY_RESEND_FUNDING_LOCKED);
                                                if let Err(MsgHandleErrInternal { ref mut shutdown_finish, .. }) = res {
                                                        // We weren't able to watch the channel to begin with, so no updates should be made on
                                                        // it. Previously, full_stack_target found an (unreachable) panic when the
@@ -4315,6 +4318,9 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                }
                                                return res
                                        }
+                                       if let Some(msg) = funding_locked {
+                                               send_funding_locked!(channel_state.short_to_id, channel_state.pending_msg_events, chan.get(), msg);
+                                       }
                                        funding_tx
                                },
                                hash_map::Entry::Vacant(_) => return Err(MsgHandleErrInternal::send_err_msg_no_close("Failed to find corresponding channel".to_owned(), msg.channel_id))
@@ -4665,7 +4671,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
                                                } else {
                                                        if let Err(e) = handle_monitor_err!(self, e, channel_state, chan,
                                                                        RAACommitmentOrder::CommitmentFirst, false,
-                                                                       raa_updates.commitment_update.is_some(),
+                                                                       raa_updates.commitment_update.is_some(), false,
                                                                        raa_updates.accepted_htlcs, raa_updates.failed_htlcs,
                                                                        raa_updates.finalized_claimed_htlcs) {
                                                                break Err(e);
@@ -5520,6 +5526,19 @@ where
                                                        }
                                                }
                                        }
+                                       if channel.is_our_funding_locked() {
+                                               if let Some(real_scid) = channel.get_short_channel_id() {
+                                                       // If we sent a 0conf funding_locked, and now have an SCID, we add it
+                                                       // to the short_to_id map here. Note that we check whether we can relay
+                                                       // using the real SCID at relay-time (i.e. enforce option_scid_alias
+                                                       // then), and if the funding tx is ever un-confirmed we force-close the
+                                                       // channel, ensuring short_to_id is always consistent.
+                                                       let scid_insert = short_to_id.insert(real_scid, channel.channel_id());
+                                                       assert!(scid_insert.is_none() || scid_insert.unwrap() == channel.channel_id(),
+                                                               "SCIDs should never collide - ensure you weren't behind by a full {} blocks when creating channels",
+                                                               fake_scid::MAX_SCID_BLOCKS_FROM_NOW);
+                                               }
+                                       }
                                } else if let Err(reason) = res {
                                        update_maps_on_chan_removal!(self, short_to_id, channel);
                                        // It looks like our counterparty went on-chain or funding transaction was
index 47e2fb33e3c7321103350865f97b5f5cc5897d14..48dab6a22fdca13163fe48e9ac95eef197fe742b 100644 (file)
@@ -564,3 +564,37 @@ fn test_scid_alias_returned() {
                PaymentFailedConditions::new().blamed_scid(last_hop[0].inbound_scid_alias.unwrap())
                        .blamed_chan_closed(false).expected_htlc_error_data(0x1000|12, &err_data));
 }
+
+#[test]
+fn test_simple_0conf_channel() {
+       // If our peer tells us they will accept our channel with 0 confs, and we funded the channel,
+       // we should trust the funding won't be double-spent (assuming `trust_own_funding_0conf` is
+       // set)!
+
+       let chanmon_cfgs = create_chanmon_cfgs(2);
+       let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+       let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+       nodes[0].node.create_channel(nodes[1].node.get_our_node_id(), 100000, 10001, 42, None).unwrap();
+       let open_channel = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, nodes[1].node.get_our_node_id());
+
+       nodes[1].node.handle_open_channel(&nodes[0].node.get_our_node_id(), InitFeatures::known(), &open_channel);
+       let mut accept_channel = get_event_msg!(nodes[1], MessageSendEvent::SendAcceptChannel, nodes[0].node.get_our_node_id());
+       accept_channel.minimum_depth = 0;
+       nodes[0].node.handle_accept_channel(&nodes[1].node.get_our_node_id(), InitFeatures::known(), &accept_channel);
+
+       let (temporary_channel_id, tx, _) = create_funding_transaction(&nodes[0], &nodes[1].node.get_our_node_id(), 100000, 42);
+       nodes[0].node.funding_transaction_generated(&temporary_channel_id, &nodes[1].node.get_our_node_id(), tx.clone()).unwrap();
+       let funding_created = get_event_msg!(nodes[0], MessageSendEvent::SendFundingCreated, nodes[1].node.get_our_node_id());
+
+       nodes[1].node.handle_funding_created(&nodes[0].node.get_our_node_id(), &funding_created);
+       check_added_monitors!(nodes[1], 1);
+       let funding_signed = get_event_msg!(nodes[1], MessageSendEvent::SendFundingSigned, nodes[0].node.get_our_node_id());
+
+       nodes[0].node.handle_funding_signed(&nodes[1].node.get_our_node_id(), &funding_signed);
+       check_added_monitors!(nodes[0], 1);
+
+       let as_funding_locked = get_event_msg!(nodes[0], MessageSendEvent::SendFundingLocked, nodes[1].node.get_our_node_id());
+       nodes[1].node.handle_funding_locked(&nodes[0].node.get_our_node_id(), &as_funding_locked);
+}
index 3868d29aab49f66789c49c970a662cba19000e2e..4d1c7c99aadf5184813c2ddeb32ccaed6483640c 100644 (file)
@@ -159,6 +159,24 @@ pub struct ChannelHandshakeLimits {
        ///
        /// Default value: 144, or roughly one day and only applies to outbound channels.
        pub max_minimum_depth: u32,
+       /// Whether we implicitly trust funding transactions generated by us for our own outbound
+       /// channels to not be double-spent.
+       ///
+       /// If this is set, we assume that our own funding transactions are *never* double-spent, and
+       /// thus we can trust them without any confirmations. This is generally a reasonable
+       /// assumption, given we're the only ones who could ever double-spend it (assuming we have sole
+       /// control of the signing keys).
+       ///
+       /// You may wish to un-set this if you allow the user to (or do in an automated fashion)
+       /// double-spend the funding transaction to RBF with an alternative channel open.
+       ///
+       /// This only applies if our counterparty set their confirmations-required value to 0, and we
+       /// always trust our own funding transaction at 1 confirmation irrespective of this value.
+       /// Thus, this effectively acts as a `min_minimum_depth`, with the only possible values being
+       /// `true` (0) and `false` (1).
+       ///
+       /// Default value: true
+       pub trust_own_funding_0conf: bool,
        /// Set to force an incoming channel to match our announced channel preference in
        /// [`ChannelConfig::announced_channel`].
        ///
@@ -187,6 +205,7 @@ impl Default for ChannelHandshakeLimits {
                        min_max_htlc_value_in_flight_msat: 0,
                        max_channel_reserve_satoshis: <u64>::max_value(),
                        min_max_accepted_htlcs: 0,
+                       trust_own_funding_0conf: true,
                        max_minimum_depth: 144,
                        force_announced_channel_preference: true,
                        their_to_self_delay: MAX_LOCAL_BREAKDOWN_TIMEOUT,